Hi there Kelly,
Thanks for reaching out to us! I’ll try to help you here.
First of all let me say I’m not sure if this is possible at all, but maybe we can find a way around it. Please start by reading this knowledgebase article about Admin roles and permissions, it should add some context to our approach.
How are you managing the roles in your site, are you using a plugin for this? Can you please link me to it? If I understood correctly you want to limit a given user role the capacity to add new or edit existing event categories, right?
Please let me know about it,
Best,
Nico